MARY Continued

Ornithopoda, Thyreophora, and Marginocephalia, provides an introduction to the dinosaurs associated with those clades. Although current dinosaur paleontologists overwhelmingly prefer cladistics, learning both classification systems is advantageous for understanding the taxonomy applied by past paleontologists, particularly those who performed work before the 1980s.

The naming of a dinosaur species is relatively difficult and requires a comprehensive knowledge not only of the anatomical features of known dinosaurs but also of the literature on previously named species. The main purpose of knowing previous work on dinosaurs is to avoid synonymiz-ing, a practice that results in too many species names, which complicate the study of dinosaurs. If a new species of dinosaur is warranted by a new discovery, the dinosaur's remains become a type specimen that is then kept as a reference for comparison with any dinosaurs discovered later that might be of the same species or differ only slightly in characters. Paleontologists can use either "lumping" or "splitting" in their identification of fossil species. Dinosaurs in particular have been subjected to both approaches, but present assessments of dinosaur species are certainly justified better than in the past.

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Determine, through discussion with your classmates and instructor, which parts of the following inanimate objects you would designate as anterior, posterior, dorsal, ventral, medial, and lateral. If you determine that some designations are not possible for the parts of some of the objects, justify why.

a. An automobile.

b. This textbook.

d. An Egyptian pyramid.

Why was the development of an acetabulum in a dinosaur hip important for an upright posture? What other changes in the appendicular skeleton had to happen in combination with the acetabulum to accommodate this major adaptation in vertebrate locomotion? Place the following appendicular bones in order of most proximal to most distal:

a. fibula, phalanges, femur, metatarsal, tarsal, tibia, ungual b. ulna, coracoid, ungual, radius, scapula, metacarpal, humerus, phalanx, carpals

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